The invention relates to a ventilation device for a fuel tank of a motor vehicle, wherein the ventilation device comprises a compensator reservoir and at least two ventilation lines opening into the latter.
A ventilation device is used to remove the gases displaced by fuel entering a fuel tank during xe2x80x9ctanking upxe2x80x9d and the gases that are emitted from the fuel during the operation of a motor vehicle. For this purpose, one or more lines are situated below the upper fuel tank wall. These lines lead from the sides of the tank to a common location at which they pass through the tank wall and lead to another tank.
A ventilation device may have two ventilation lines and three compensator reservoirs is known. The ventilation lines open out on both sides of the tank. From there, they lead to the opposite side of the tank and curve back again into the center where they open into a central compensator reservoir. In the curved sections near the side walls the lines include a widened section which is likewise designed as a compensator reservoir. This line routing has the effect that when the tank is inclined ventilation is ensured. One disadvantage is that this device is only suitable for tanks of relatively simple construction. Another disadvantage is that the routing of the ventilation lines is very complicated because of the labyrinth-like course the lines must take. Further disadvantages, caused by the inclusion and arrangement of a number of compensator reservoirs, include that the device is complicated to manufacture and that the installation of the device in a fuel tank requires a high outlay.
The invention provides a ventilation device which is of simple construction, can be installed easily and ensures reliable ventilation and maximum filling of the fuel tank under all circumstances.
The ventilation device may be used in a fuel tank. In one embodiment it comprises a compensator reservoir in the fuel tank and at least two ventilation lines opening into the compensator reservoir. In this ventilation device, the ventilation lines run from the vicinity of at least one of the side walls of the fuel tank to the compensator reservoir. Advantageous refinements are also disclosed herein.
The ventilation device includes a compensator reservoir which is arranged in the interior of a fuel tank and into which at least two ventilation lines open. The fuel tank includes a first side wall and a second side wall. The compensator reservoir extends from the first side wall to the second side wall of the fuel tank. The ventilation lines include a first opening and a second opening. The ventilation lines are arranged such that at least one of the first openings of the ventilation lines is always situated above the fuel level for all possible inclined positions of the fuel tank. The ventilation lines extend from the vicinity of one of the side walls to the vicinity of the other side wall, wherein the first opening is in the fuel tank and the second opening is within the compensator reservoir.
The ventilation device, therefore, enables reliable ventilation for static and dynamic stressing of the fuel tank and at the same time permits a particularly high filling quantity in the fuel tank. Moreover, the geometrical configuration of the compensator reservoir makes simple routing of the ventilation lines possible, with the result that complicated return lines are superfluous. At the same time, only one compensator reservoir is necessary. Because of its simplicity, the entire ventilation device is distinguished by low production costs, low weight and simple installation.
The compensator reservoir advantageously has a widened section which is used as a liquid trap and via which any fuel which has passed into the compensator reservoir is sucked into the interior of the fuel tank, preferably via an ejector or directly via the fuel pump. To ensure that the ejector or fuel pump does not allow the compensator reservoir to be filled to overflowing when, for example, the vehicle is parked on a slope, a nonreturn valve is used in the extraction line of the widened section.
The ventilation device is particularly simple if the ventilation lines enter into the compensator reservoir at any desired location, preferably at the widened section, and are then guided in the compensator reservoir until they are close to the side wall opposite the side wall in the vicinity of the first opening of the ventilation line. When the ventilation lines are arranged diagonally, the above-described system ensures satisfactory ventilation of the fuel tank at maximum filling level and due to the static and dynamic stresses, optimally prevents the fuel tank from being filled to overflowing.
Depending on the shape of the tank, the diagonal ventilation arrangement can also be formed using four predominantly diagonal ventilation lines while retaining the abovementioned, positive properties. In this case, the ventilation lines are arranged starting in the comers of the fuel tank and running diagonally toward the compensator reservoir. The compensator reservoir may be arranged in any desired manner with respect to the longitudinal axis of the vehicle and may also be of x-shaped design with the individual arms of the compensator reservoir extending toward the ventilation lines.
It is furthermore advantageous if the compensator reservoir has a float/roll-over valve.
The invention is explained in greater detail using three exemplary embodiment and the associated Figures.